Dents may occur in metal surfaces, and removal of the dents may be desirable for aesthetic or performance reasons. For example, airplane wings may become dented during operational service. Dents in airplane wings may decrease lift and may increase drag. As a result, it would be desirable to remove dents from airplane wings.
It is currently known to remove dents in metal surfaces by “pulling” the dents in the surface of the metal with a magnetic field generated by a coil of an electromagnet. Examples of known coils are disclosed in U.S. Pat. Nos. 4,061,007 and 4,123,933, the contents of which are hereby incorporated by reference.
Referring to FIG. 1, a prior art electromagnetic coil 10 includes an annular wrap of layers 12 of a conductor 14. These coils are visible through the head 13 of the coil 10. The coil 10 defines notches in the annular wrap that serve as foot 18. The foot 18 and is the locus on the electromagnetic coil 10 used for pulling dents.
However, present coils have presented some shortcomings. For example, known coils are expensive to fabricate and have reached their maximum power level. Further, current coils are subject to a high failure rate. Current coils may fail if the coil moves excessively in its housing while the coil is energized to pull a dent. Further, dielectric material within the coil may become damaged from high heat and stresses generated during the firing process. Also, current coils may experience reduced performance. For example, current coils may generate excessive amounts of heat and may generate a reduced magnetic field due to mechanical property changes at elevated temperatures.
Referring now to FIG. 2, a failure 20 of the prior art electromagnetic coil 10 is illustrated. The annular wrap of the layers 12 of the conductor 14 is a principal feature allowing susceptibility to the failure 20. The failure 20 occurs when an applied electromagnetic force pulls one of the layers 12 of the conductor 20 from the coil 10.
Therefore, there is an unmet need in the art for a coil for an electromagnetic dent remover that is less expensive to fabricate and has a lower failure rate than currently known coils, and has increased performance over currently known coils.